It's an USB Wireless adapter? I had to throw one of it outside the window because of the same problem, and got a PCI WiFi card.

That's not giving me problems anymore

I think that USB adapters overheat (and stops working, thus losing connection), when the WiFi signal is too weak, and you have to disconnect and reconnect it to make it work again. And after a while, this trick didn't even work anymore :/

upgrade the firmware on your router.
try a 7dbi atenna. I have a d-link and I get reception throughout my 1800 sq ft house even with doors closed.
do not use windows to connect to the internet, try using the netgear software that should have come with your adapter.

Make one of those bouncer things that go on the antennas. Google something like "wireless router parabolic bouncer" for more info. People have posted diagrams and such of exactly how to make the best reflectors.